The present invention relates to a notching press machine for punching, stamping, or die cutting so called “notches” in the inner or outer peripheries, or both, of typically circular or annular work pieces, such as electric motor and generator laminations or the like. Many notching presses of differing designs are known in the art.
Many notching presses known in the art are comprised of a “C” shaped press frame, commonly called a “gap frame press”, a driven eccentric crankshaft, a linearly guided slide or ram for mounting an upper or punch section of a tool, a linkage type transmission mechanism for transforming the rotating eccentric crankshaft motion into a linear reciprocating motion of the slide or ram, and a mounting location or bed section of the press frame for mounting the stationary lower or die section of a tool. These components cooperate to move the upper or punch section of a tool into and out of engagement with the lower or die section of the tool and the work piece which is positioned there-between. Known gap frame presses typically are driven by a continuously rotating crankshaft drive motor and sometimes a flywheel, a clutch which when engaged drivingly connects the drive motor or flywheel to the crankshaft for rotating the crankshaft, and a brake mechanism for stopping the crankshaft after the clutch has disengaged.
Many notching presses further comprise an indexing mechanism arranged to hold a work piece and for the intermittent rotation of the work piece while the tool is out of engagement with the work piece and to hold the work piece in a proper angular position when the tool is engaged with the work piece to produce the desired final work piece shape.
Many notching presses further comprise a stationary base to which the gap frame press attached and is arranged for sliding in a typically horizontal direction, and in particular in a direction perpendicular to the motion of the press ram, in order to vary the distance between the tool and the indexing mechanism axis of rotation to facilitate the processing of work pieces of varying diameters or for the punching at multiple diameters of a single work piece.
Notching presses are typically capable of accepting exchangeable tools to perform the cutting or stamping of the work piece. Different tools may require different so-called “shut height” settings. Press shut height is the distance, measured in the direction of ram motion, from the end of the ram to which the upper or punch section of the tool is attached to the mounting location or bed section of the press frame to which the lower or die section of the tool is attached when the ram is in the closest or “shut” position. Many notching presses known in the art comprise an adjustment mechanism for changing the press shut height to permit the use of exchangeable tools. Typically the adjustment mechanisms are disadvantageously manually adjusted.
It is desirable for notching presses to operate at relatively high production rates generally measured in “strokes per minute.” To achieve maximum production rates, it is desirable to configure a notching press with minimal press stroke length. Press stroke length is the distance marked by the farthest ends of the reciprocating movement of the press ram. Minimizing the stroke length of a notching press ram increases the difficulty of loading and unloading of the work piece between the upper and lower section of the tool. Therefore, it is common for notching presses to comprise a ram lifting mechanism to further move the ram away from the work piece upon completion of all punching operations to be performed on the individual work piece. The finished work piece may be then easily unloaded and a next work piece may be loaded for processing after which the ram lifting mechanism moves the ram to the desired starting position for subsequent crankshaft rotation and stamping operations to proceed. Current known in the art ram lifting apparatus lift the ram in a fixed amount.
As previously described, the notching press tool typically includes two sections: an upper or punch section and the lower or die tool section. Typically, the lower tool section is rigidly mounted to a bolster plate that is rigidly mounted to the press bed. The upper tool section is typically rigidly mounted to the press ram thereby subject to reciprocating and typically vertical, motion into and out of engagement with the lower tool section. Guiding of the press ram is provided to ensure and maintain proper alignment of the upper and lower tool sections. Any deviation in the alignment of the upper tool section with respect to the lower tool section will reduce the cutting accuracy of the tool. Additionally, this deviation may cause damage to the tool. The successful stamping of any work piece is dependent on the ability for the upper tool section and the lower tool section to maintain proper alignment.
The generally “C” shaped press frame of typical notching press, while necessary for the convenient loading and unloading of a work piece, will necessarily bend or deflect due to the high forces generated in the stamping operation. For example, during the time of impact of the press ram and upper tool section onto a work piece, a typical gap frame press will experience an angular deflection and subsequently the crankshaft will be displaced in a direction perpendicular to the line of action of the press ram. Furthermore, in many known such presses, the ram guiding is disadvantageously subject to this deflection of the frame causing miss-alignment of the upper and lower tool sections.
To overcome these and other disadvantages of presses known in the art, a notching press machine is depicted in the enclosed figures.